Power transmission



March 25, 1941. E. L. ROSE POWER TRANSMISSION Filed latch 28, 1936 4Sheets-Sheet 1 INVENTOR Enwnv L. Ross BY ATTORNEY 7f'fM .h125,1941, sE2,236,489

. POWER TRANSMISSION Filed larch 28, 1936 I 4 Sheets-Sheet 2 INVENTOREDWIN L. Poss ATTORNEY 1 March 25, 1941. 1-; os: 2,236,489

' POWER TRANSMISSION Filed March 28, 1936 4 Sheets-Sheet 3 E PI 5INVENTOR EDWIN L. Poss ATTORNEY March 25,1941. Emos "2,23*s,4s9

POWER TRANSMISSION Filed march 28, 1936- 4 sheets-sheet 4 ATTORNEYPatented 25, 1941 UNITED STATES PATENT OFFICE I 2.235,. oma lwl'fififimm.

Waterbury Tool Company. Waterbury, Conn, a

corporation or Connecticut Application ms as. use, Serial No. 11,41:

11 Claimt. (Cl- 254-172) sion deviceand control therefor particularlyadapted to hoisting an object while relative movement between the objectand the hoisting device is occurring. A device ofthis character isuseful. for example, on ship board for the purpose of lifting floating'ohiectssuch as boats, airplanes,

'etc., from a rough sea. The inventionis shown and described as adaptedto:- this use, although it will be understood that the invention may beused for other purposes.

In lifting floating objects from rough seas, par.- ticularly objects ofa comparatively fragile character, such as a seaplane, it is necessaryto insure that the means, usually a cable, which connects the object tothe hoist is maintained taut at all times while the object is moved upand down relative to the hoist by the action of the waves. Uriless thisresult is insured at all times, it is possitale and frequently occursthat when the hoist is operated to lift the object out of the water, asudden jerk is given to the object and the connecting means, which maybe of suiiicient magnitude to rupture the connecting means or to damagethe object by pulling out the-ring, or other facilities for attachmentto the connecting means. Devices heretofore proposed for solving thisproblem, have' been so constructed as to require a dimcult manualoperation of the controls, when changing from constant tension tohoisting, if dangerous jerks on the object are to be avoided.

Furthermore. such devices under certain conditions of operation havebeen known to permit slack and consequent jerking to occur.

It is an object of the present invention to provide a power transmissiondevice for driving a hoist and including control devices for preventinga sudden Jerk upon the object being hoisted under any condition ofoperation.

A further object is to provide a control system for a device of thischaracter by which the operation of changing over from a condition atwhich a predetermined tension is maintained in the hoisting maybe madeonly at the instant when the hoisting speed at constant-tension falls toth value at which positive hoisting is done.

it further object is to provl'de a control for a. device of thecharacter described providing means for taking up slack which mightoccur due-to wave action after hoisting is started, that is to say, toprovide a control. which, during hoisting,

55 has no upper limit to the tension which may be hoisting connection tothe condition of positive.

hoist comprisinga maintained on the hoisting c' tion but main- I tains alower limit of tension thereon.

It is also an object to provide such a control means which operates inresponse to the loading and unloaiiina of the hoisting connection by the5 mil weight of the object being hoisted and does not require manualoperation.

A further object is to provide a control device for a variabledisplacement pump in which the displacement may be varied either inresponse-to 10 working pressure to maintain a substantially constantpressure or may be controlled to maintain the pressure above apredetermined minimum and to provide manual means for selective- I lytransferring the control from one condition 15 to the other. 1

- Further objects and advantages of the present invention will beapparent from the following description, reference being had to theaccompanying drawings wherein. av preferred form of the presentinvention is clearly shown.

In the drawings:

Fig. 1 is a side view ofa hoist embodyi a preferred iorm of the presentinvention.

Fig. 2 is a cross section on line 2-2 of Figs. Sand 4 showing a combinedfluid motor and hoi forming part of the present invention.

Fig, 8 is a cross section on line 3-3 of Fig. 2.

Fig. 4 is across section on line 4-4 ofliig. 2.

Fig. 5 is a side view partly in section of a variable displacement pumpembodying the present invention.

. Fig. 8 is a fragmentary sectional view of acontrol mechanism forthe'pump illustrated in Fig. 5. I

Fig. 7 is a iragmentary sectionalview oi a latch mechanism taken on line1-1 of Fig. 8.

Fig. 8 is a fragmentary sectional view on line A H of Fig. 'i. Fig. 9 isa fragmentary sectional viewon line 9-4 of Fig. "l.

e Fig. 10 is a fragmentary sectional view on'line il-il of Fig. 6showing the parts in one position.

Fig. 11 is a view corresponding to Fig. 10 showing the parts in a secondposition.

Fig. 12 is a view corresponding to Fig. 10 showing the parts in a thirdposition. I

Fig. 13 is a fragmentary cross section-on line lt---ilofl"lg.8. v

Referring now to Fig. 1 there is illustrated a.-

tachedtoamast II ofaship. Awinch-il is'suitably mounted on the deck ofthe ship' and has a drum. It over which is wound a cablejforming part ofa connecting means between the winch and the object to be lifted. CableIt is threaded crane boom ll 'pivotally at- .50

fluid motor.

over pulleys 20 and I2 and through a pulley block 24 to which isattached a hook or other load attaching means N. The drum It includes ahydraulic motor incorporated in the interior of the drum by which thedrummay be rotated in either direction. This motor which will bedescribed in detail hereafter is of variable displacement and a pressureresponsive valve is provided within the drum for controlling theeffective displacement of the winch operating motor. Supply and returnconduits 28 and 80 connect the hydraulic motor to a variabledisplacement pump 82. the pump being operated by a suitable prime moversuch as a substantially constant speed electric motor 34. The pump 32may be of any suitable construction and is illustrated as of thewellknown Waterbury type which includes a tilting box 38 by means ofwhich the piston stroke and consequently the displacement oi the pumpmay be varied.

Referring now to Figs. 2, 8, and 4, the internal construction oi thefluid motonis there illustrated. The winch it includes a pair ofpedestals 31 upon which is rigidly mounted a stationary central tubularsupporting member 88. The drum I6 is pivotally mounted on the tubularsupport 38 by means oi bearings ll and II. The drum I6 is made in twohalves each including a dished imperforate web H, and ll connecting therims 48 and S with the bearings 40 and 42. The two halves of the drumare rigidly secured by threads to an internal ringgear II. Meshing withthe ring gear 52 is a set of pinions l4 and It (Fig. 3), each 01' whichis journailed upon a stationary trunnion II. The sides of the ring gear52 and the ends of the pinions II and It are enclosed by a pair oistationary plates I and 82 which are rigidly secured to the supportingmember ll. The space between the plates I and ".which is not occupied bythe ring gear I! or'the pinions l4 and It is occupied by a flller blackn to which the plates II and I! are rigidly bo ted.

The block 64 is formed with a pluralty of fluid L passages communicatingwith the meshing points of the various pinions with the ring gear toprovide suitable fluid inlet and outlet connections. For this purposepassages l (Fig. 3) communicate with the pinions I on one side of theirmeshing points with gear It, while passages ll communicate with thepinions I. at the same side of their meshing points with the gear II.

Passages 10 (Fig. 4) communicate with each of the pinions It and II atthe opposite sides of their meshing pointswith gear ll. Passages llcommunicate by means 01' passages I! with the interior of the supportingmember ll through holes I4 iormed therethrough. Passages it communicatewith chambers It each of which in turn communicates with the interior oithe supporting member 88 by passages ll iormed in the block 04 andpassages ll formed in the supporting member 8|. The passages llcommunicate with a chamber 82 which in turn communicates by means oipassages II and II, and holes I! and II in the supporting member I. withthe interior or the latter. Within the hollow interior oi the supportingmember it there is mounted a pressure responsive; valve morallydesignated as II i'or controlling the path 0! fluid through the valve ucomprises a bore having portions as; a: and u 01' different respectivediameters. Portion ll is of the smallest diameter and the portion II thelargest while the portion II is 01' intermediate diameter. Freelyslidable within the central bore is a valvemember 95 carrying pistons88, I! and I" fltting the bores ll, 82 and I4 respectively. The piston88 is i'reely slidable on the valve member II, a spring it! normallyholding the piston ll against a shoulder I formed on the member OI.Piston ill! carries a guide spider I for guiding the righthand end oithe member 05 when the piston I0! is out 0! the bore 04. A spring II! ismounted in the left-hand end of the bore It to urge the valve member 08to the right and is adjustable by means of an adjutsing screw H0. Thepassages 8| communicate with the central valve bore at an enlargedchamber between the portions 0! and M. The passages 14 communicate withthe central valve bore at the portion 04 while the passages Itcommunicate with the central valve bore at theportion Q2. The passage I!communicates with an annular passage III formed by a sleeve member Iwhich also forms a guide for the spider I". Passage ii! communicateswith the return conduit 30 through passages, not shown, formed in theright-hand pedestal 81. Supply conduit 28 communicates with the bore llthrough the central passage in member ill.

The operations of the parts shown in Figs. 2, 3, and 4 is such that iifluid under pressure be supplied through the conduit 28 to the righthandend of the central bore 01- the valve ll with the parts in the positionillustrated in Fig. 2. a passage is constantly open to the two pinions Ithrough passages I4, I! and I. So long as the pressure existing inconduit 28 and acting on piston "I is insuiflcient to overcome the forceof the spring Ill holding the parts in the position shown in Fig. 2. theentire quantity of fluid supplied through the conduit flows to the twopinions l4 and causes them and the ring gear 82 to revolve clockwise inFig. 3. The pinions deliver the fluid supplied to. them to conduits IIfrom which it flows through chamber I! and passages I4, 8!, l1 and illto the return conduit 30. The drum is thus caused to revolve clockwisein Fig. 3.

During such movement the pinions It and ring gear I! act as gear pumpswithdrawing fluid from passages It and delivering it through passagesll. chamber l2, passages 84, II, and II, portion I! or the central valvebore. passages 8| and. II to chambers II. and passages II, This circuitis of substantially negligible resistance so that the-ten pinions. IIare by-passed and ineifective so far as operation of the drum II isconcerned. For a given quantity of fluid supplied through the conduitthe speed of operation of the drum ll under these conditions istherefore comparatively high since the entire quantity oi fluid suppliedto the hydraulic motor is operative upon only two pinions thereoi andthe eirective displacement of the motor is consequentiy small. While thehoist may be operated at high speed under these conditions, the loadwhich it may handle is comparatively lim-' ited.Assoonastheloadincreasestoapredetermined value which is determined bythe area than the amount withdrawn trom condult as by the pump 32. Theexcess quantity is permitted to by-pass irom portion 32 of the centralvalve bore to the passages 88 by pushing the piston 88 to the right onstem 35'against the spring I82 until such time as the entire quantity oifluid returning from the twelve pinions is taken in by the pump throughthe conduit 38.

At this time the,piston 38 moves completely into portion 32 of thecentral valve bore, thus effectively sealing the high pressure fluid inthe portion 34 from the low pressure fluid in theportion 32. Under thiscondition the fluid is distributed to all twelve of the pinions 84 and88.

The path of the fluid to and from the pinions 54 is the same as thatpreviously described. The path of the fluid-to and from the pinions 88is the same as the by-pass path previously described ex-' cept thatfluid is supplied to the passage 88 from the portion 34 of the centralvalve bore and fluid returning through the passages 84 and 88 goes tothe return conduit 38 through passages iI2. Whenever the pressure inconduit 28 isreduced to a predetermined value lower than the value atwhich valve 35 moved to the left, the valve moves back to the positionillustrated in Fig. 2. The difierence in the points at which the valvelifts and falls is due to the difference in area between the-pistons I88and 38. The piston areas may be so chosen with regard to thedisplacement ratio of the motor. in this case one to six. that thedifference in cable tension between the openof cable tension at whichthe ten pinions operate on a fluid pressure which is reduced bythrottling at the valve 88. Thus if the areas are such that the valve 38rises at three times the pressure at which it i'alls with a one to sixdisplacement ratio, the cable tension required to maintain the valvefully open will be twice the tension required to crack the valve open.

Referring now to Figs. 6 through 13inclusive, the control mechanism forthe pump 32 is illustrated. The tilting box 38 carries an operating studII8 to which is connected by means of a sliding and pivoting joint 8' avertically slidable operating stem I28. The lower end of the stem I28 isformed with a piston I22 slidable in a cylinder bore I24 which is incommunication with the supply conduit 28; through'a passage I28 formedin the casing of the. :pump. The stem I28 is formed with a shoulder I28against which a spring plate I38 abuts. A spring I32 has its lower endabutting the spring plate I38 and its upper end abutting a spring plateI34 adiustably secured to the pump casing. The stem I28 projects throughthe spring plate'I38 and carries two sets of yield-' able latches I36and I38 (see Figs. '7, 8 and 9). the latches I36 and I38 are disposed atright angles to one another and vertically spaced sothat the latches I36may engage the upper side of a ledge I48 while the latches I38 mayengage may be locked in any one of three angularly spaced positions bymeans of a spring pressed,

81 and manually operable detent I82. The sleeve I44 carries a bevel gearI84 at its upper end which meshes with a bevel gear I88 carried by ashaft I88 which may be operated by a hand wheel I88. A flange I82 whichis rotatably mounted between a supporting sleeve I88 and a cover memberI68 restrains the sleeve I44 against vertical movement.

The ledge I48 is interrupted at points I18 and I12 (see Fig. 13) in.order to permit the latches I38 and I38 to pass the ledge in eitherdirection of movement in certain positions of the operating.

handle I48. Thus, in the position illustrated'in Fig. 10 which may becalled the constant tension position. both the latches I38 and I38 areopposite the portions I18 and I12 respectively so that the stem I28 mayreciprocate freely through its full range of movement. In the positionillustrated in-Flg. 11 which may be termed the manual control position,both the latches I38 and I38 are opposite portions of the ledge I48 sothat the tubular member I42 may be rigidly secured to the stem I28. Inthe position illustrated in Figs. 12 and 13 which may be termed thepick-up position, the interrupted portions I18 are in register with thelatches I38 while portions of the ledge I48 are in register with thelatches I38. In this position the stem I28, after it has once moved thelatches I38 downwardly past the ledge I48, is preventedfrom movingupwardly again beyond the-point where the latches I38 engage theibottomof the led e I48 although the stem I28 is free to move downwardly fromthis position at any time.

' It will be seen that in the constant tension position of the handleI48, the position 01' the tilting box 38 is under the sole control ofthe piston I22 and the spring I32. In the manual control position of thehandle I48, the position of the tilting box 38 once the latches I38 andI38 have been engaged with the ledge I48 is under the sole control ofthe hand wheel I68. In the pick-up position the movement 01' the tiltingbox upwardly is limited by the position of the ledge I48 so long as theworking pressure of the pump is sufflcient to overcome the force of thespring I32 and hold the latches I38 in engagement with they ledge I 48.Upon' a drop in pressure below this point, the position of the tiltingbox is determined by the pressure through the medium of the piston I22and the spring I32.

' It will be noted that if the handle I48 is turned from constanttension. position to pick-up position at an instant when they latchesI38-are above the ledge I48 that the tilting box remains under thecontrol of the piston I22 andspring I32 until such time as the stem I28has moved; downwardly to bring the latches I 38 beneath the ledge I48and has again started upwardly to engage the latches I38 with the ledgeI48.

In operation of the device as a'whole the motor 34 is placed inoperation, the lever I48 is .placed in manual control position and thehand neutral oitzero displacement position;

When it is desired toJlift a seaplane floating alongside the ship (theship and the plane being either traveling through the water'at the samerate 'or both standing still except for wave movements), a lightthrowing line is attached to the wheel I88 is turned to bring thetilting box into hook 26 and thrown overboardto the pilot of theairplane. With handle I48 in manual control position the hand wheel I68is then turned to operate the'tubular member I42, stem I28 and tiltingbox 38 upwardly to pump fluid in the reverse direction through thewithin' the hoist drum l8 and thus cause the hook I! to be lowered tothe plane. The pilot then will the hook with a ring or other attachingmeans by which the plane isto be lifted and the operator on deck movesthe control handle I to constant tension position. This movement freesboth the latches I" and m from the ledge ill and since there is no leadon the came II and consequently no pressure in the cylinder I, thespring it! forces the stem Ill downwardly to move the tilting box ll. tofull stroke in the hoisting direction. The valve it is at this time inthe position illustrated in Fig. 2 due to the low pressure in conduitis. 'As a result cable II is wound in at a rapid rate. As soon astheslack is taken up sumciently to produce a light tension on the same,that is, a light load on the winch, the pressure in conduit 2| andcylinder Ill rises to a value suflicient to overcome the force of thespring I32 and moves the tilting box to neutral position. As the tensionincreases and decreases due to alternate raising and lowering of theplane relative to the boom it by the wave action, the pressure inconduit 28 and cylinder Ill rises and falls causing a correspondingmovement of the tilting box it. Thus, when the pressure rises due toawave receding and permitting the plane to fall, the stem III is movedupwardly bringing the pump into stroke in a lowering direction causingcable to be paid out at a rate corresponding to the pressure. The rateof the spring in and the preloading thereof is such that the variationin spring pressure between full stroke in the hoisting direction and runstroke in the lowering direction is small compared to the average springpressure so that the tension in the cable is maintained at a value whichis very nearly constant.

When it is desired to hoist the plane from the water, the handle ill ismoved to pick-up position. This may be done without regard as to whetherthe plane is rising or falling relative to the boom at the instantduring which the hendie I" is turned. Thereafter as soon as the planerises on a wave and its upward speed. as it approaches the crestthereof, falls to the point corresponding to the setting of the tubularmember I, thestem III ispreventedfrohirisingfurther by engagement of thelatches m with the ledge Ill. Before shifting the handle I to pickupposition, the operator will have set the tubular member in at a'positioncorresponding to the hoisting speed at which he desires to pick theplane of! the water. This may be done by oper-- ating the handwheel IIIwhile lever I is in constant tension position. In the latter positionthe tubular member in is, of course, un-

connected to the tilting box It. It will be seen.

that, even if the handle I be turned to pickup position while the planeis descending on a wave, it is impossible to produce an undesirable Jerkon the cable "became the oableispermittedto pay out and haul in asrequired for the maintenance of the constant tension until theplaneagainrisesonawaveandtheupwardspeedfallsoifuntiiitreachesthespeedatwhich it is desired to plcktheplane oi! the water.

.Assoonastheweightof the planecomeson the hook it, the pressureinconduit it rises to a point above the pressure which is maintainedduring constant tension operation and the valve ll lifts as previouslydescribed causing the fluid supplied to the hoist motor to bedistributed to all twelve of the pinions rather than to the two pinionss4. 'rii speed of hoisting is thereby further decreased and the loadwhich may be lifted with a given pressure in the conduit is iscorrespondingly increased. If the wave amplitude is small so that theamplitude of movement of the tilting box it during constant tension issmall, the operator may be forced to set the tubular member I at aposition correspondin to a very small stroke in the hoisting direction.In this case after the plane has been picked up and the valve II hasshifted to twelve pinion operation of the hoist motor, the hand wheel I"may be moved to increase the stroke in the hoisting direction so as toraise the plane at a faster rate It'will be seen that by means of thehandle Ill, the winch driving means may be rendered subiect to threedifferent methods of control. When the handle I is in constant tensionposition (Fig. 10), the control is entirely load responsive. The speedof the winch driving means is automatically varied by the piston inandspring It! to follow the movements of the plane on the water in sucha.manner that the cable tension is maintained substantially constant.

When the handle I is in pick-up position, the control is lead responsiveonly below a predetermined low value of load. The speed of the winchdriving means is subject to control by the piston in and spring I" atthe lower values of cable tension but as the cable tension increaseswith the decrease in upward speed of the plane, the latches I" preventfurther decrease in upward speed of the winch. Oi necessity, therefore,the load on the winch increases to the value corresponding to fullweight of the plane. When the handle I is in manual control position.the winch driving means is subject entirely to manual control throughthe handwheel m.

If at any time after the plane has been picked off the water a largerwave strikes the bottom oftheplaneandraisesitfasterthanitisbeinghoisted. the valve ll begins to shift to two pinion operation at a cabletension value substan-v tially twice the tension normally maintainedduring constant tension operation by the piston iii and spring I". Thus,the speed of hoisting is increased and the cable is maintained tauteventhoughtheplanebeliftedbythewave faster than the normalhoisting'speed. As soon astheupwards'peedofthewavedropstothe' hoistingspeed, valve ll again opens due to the increased pressure and hoistingis continued as before. Should an unusually large wave strike the shipimmediately after-hoisting has started it is possible that the operationof the winch motor on two pinions with the tilting box set at theposition where latches m are against the ledges I, may not be fastenough to keep the cable taut. In such ,an event the stem I2! is free todmend. increasing the hoisting speed as required to keep the cable taut.Since the shift to two pinion operation isniade at a higher cabletensionthan that at which stem i2! is per-.

the plane lowered to the deck. At anytime between the time when theplane is sumciently high above the water so that the highest possiblewave cannot reach it and the time when the plane is set down on thedeck, the lever J48 may be thrown to manual control position in whichthestem I20 is locked to'the tubular member I42 for movemnet therewith inboth directions. Thereafter cable l8 may -be paid out to disengage thehook 26 from the ring on the plane and the cycle of operation repeatedas desired.

While the form of embodiment of the inventionas herein disclosed,constitutes a preferred form, it is to be understood that other formsmight be adopted, all coming within the scope of the claims whichfollow. It will also be understood that where the claims-define anobject subject to varying external forces counteracting the pull (of thedevice) that this and similar expressions refer to conditions not onlywhere the external forces are acting in a direction opposite to the pullof the device on the object but also where the external forces may be,at times, of

opposite sign and assisting the pull of the device. What is claimed isas follows: 1. In a device for pulling on an object while subject tovarying external forces counteracting the pull the combination of a.winch, variable speed means for driving the winch, automatic meansresponsive to load on the winch for controlling-the speed and directionof the driving means to maintaina substantially constant, light load onthe winch, additional means for controlling the speed and direction ofthe driving means independently of the load and a single control memberfor rendering the driving means subject to control either entirely loadresponsive, or load responsive only below a predetermined low value ofload, or entirely independent of load.

2. In a device for pulling on an object while subject to varyingexternal forces counteracting the pull the combination of a winch,variable speed means for .driving the winch, automatic means responsiveto load on the Winch for controllingthe speed and direction of thedriving means to maintain a substantially constant, light load on thewinch, means for limiting. the operationof said automatic means to arange of speed above a selected minimum pulling speed and manuallyoperable means for rendering said limiting means effective, only afterthe automatic means has brought the speed of the winch into .saidlimited range.

' 3. In a device for pulling on an object while subject to varyingexternal forces counteracting the pull the combination of a winch,variable speed means fordriving the Winch automatIc means responsive toload on the winch for controlling the speed and direction of the drivingI means to maintain a substantially constant, light load on the winch,means for limiting the operation of said automatic means to a range ofspeed above a'selected minimum pulling speed, manually operable meansfor rendering said limiting means eil'ective only after the automaticmeans has brought the speed of the winch into said limitedrange, andadditional means for controlling the speed of the winch independently ofthe load; in

subject to varying external forces counteracting the pull thecombination of av winch, variable,

4. In a device for pulling on an object while' to maintain asubstantially constant, light load on the winch, means for limiting theoperation of said automatic means to a range of speed above a selectedminimum-pulling speed, manually operable means for rendering saidlimiting means effective only after the automatic means has brought thespeedof the winch into said limited range, and additional means forcontrolling the speed of the winch independently of the load, said lastmentioned means including mechanism operable to vary the minimumpullingv speed to which the winch is limited when the limiting means iseffective.

5. In a device for pulling on an object while subject to varyingexternal forces counteracting the pull the combination of a winch,variable speed means for driving 'the winch, automatic means responsiveto load on the winch for controlling the speed and direction of thedriving means to maintain a substantially constant, light load on thewinch, means manually operable for causing the winch to positively pullin the object at a predetermined pulling speed, said means beingineifective'to start pulling until the automatic means has reduced thespeed to said predetermined pulling speed, and additional means forselectively varying said predetermined. pulling ing ineffective to startpositive pulling until the automatic means has reduced the speed to saidpredetermined pulling speed, and additional means'for selectivelyvarying said predetermined pulling speed, said last means includingmechanism operable for manually controlling the speed and direction ofthe winch independently of the load. i

'7. In a device for pulling on an object while subjectto varyingexternal forces counteracting the pull the combination of a winch,variable speed fluid power transmission means for driving the winch,automatic means responsive to load on the winch for controlling thespeed and stantially constant, light load on the winch, means manuallyoperable for causing the winch to positively pull in the object at apredetermined pulling speed, saidmeans being ineffective to startpositive pulling until the automatic means has reduced the speed to saidpredetermined speed, and additional means for selectively varying saidpredetermined hoisting speed.

8. In a device for pulling on an object while subject to varyingexternal forces counteracting the pull the combination of a winch,variable speed fluid power transmission means for driving the winch,automatic means responsive to load direction of the driving meanstomaintain a subon the winch for' controlling the speed and direction ofthe driving means to maintain a substantially constant, light load onthe winch, means manually operable for causing the winch to positivelypull in the object at a predetermined pulling speed, said means beingineffective to start pullingluntil the automatic means has reduced thespeed to said predeterm'ined pulling speed, and additional means Iorselectively varying said predetermined pulling speed, said last meansincluding mechanism operable for malnually controlling the speed anddirection of the winch independently of the load.

9. In a crane for picking up objects floating in a sea-way thecombination of a winch drum, a cable windable on the drum, and havingmeans for attachment to a floating object, a fluid motor for driving thewinch drum, a variable displacement pump for supplying fluid to thefluid motor, means for driving the pump, and fluid pressure responsivemeans for controlling the pumpldisplacement to maintain a substantiallyconstant light tension in the cable prior to lifting the ohject from thewater, whereby the cable is mantained taut at the instant the object ispicked on? the Seaway.

10. In a device for pulling on an object while subject to varyingexternal forces counteracting the pull the combination of a winch,variable speed means for driving the winch, automatic means responsiveto load on the winch for con-- trolling the speed and direction of thedriving means to maintain a substantially constant, light load on thewinch, means for preventing said automatic means from causing the winchto operate in a paying-out direction, and manually operatable means forrendering said last means effective only after the automatic means hascaused the winch to operate in a winding-in direction.

11. In a device for pulling on an object while subject to varyingexternal forces counteracting the pull the combination of a winch,variable speed means for driving the winch, automatic means responsiveto load on the winch for controlling the speed and direction of thedriving means to maintain a substantially constant, light load on thewinch, means for preventing said automatic means from causing the winchto operate in a paying-out direction, and manually operatable means forrendering said last means effective only after the automatic means hascaused the which to operate in a winding-in direction, and additionalmeans for controlling the speed of the winch independently of the load.

EDWIN L.

